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fix: warn on stderr when discovery cache write fails #191

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Bortlesboat wants to merge 1 commit into from
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fix: warn on stderr when discovery cache write fails #191

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10 changes: 10 additions & 0 deletions .changeset/fix-discovery-cache-warning.md
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Original file line number Diff line number Diff line change
@@ -0,0 +1,10 @@
---
"@anthropic/gws": patch
---

Warn on stderr when discovery cache write fails

Previously, the error from writing the discovery document cache was
silently discarded (`let _ = e`). Now prints a warning to stderr so
users are aware their cache is not persisting (e.g., due to disk full
or permission issues).
5 changes: 2 additions & 3 deletions src/discovery.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -241,10 +241,9 @@ pub async fn fetch_discovery_document(
alt_resp.text().await?
};

// Write to cache
// Write to cache (non-fatal — warn if it fails)
if let Err(e) = std::fs::write(&cache_file, &body) {
// Non-fatal: just warn via stderr-safe approach
let _ = e;
eprintln!("warning: failed to write discovery cache to {}: {}", cache_file.display(), e);
}
Comment on lines 245 to 247
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@gemini-code-assist gemini-code-assist bot Mar 6, 2026

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high

While eprintln! is a good step up from silently ignoring the error, it can panic if writing to stderr fails (e.g., if the pipe is closed). Given the operation is described as 'non-fatal', a panic would be an undesirable outcome. To create a truly 'stderr-safe' warning that won't panic, it's better to use writeln! with std::io::stderr() and ignore the Result. This ensures that a failure to write the warning doesn't crash the application.

Suggested change
if let Err(e) = std::fs::write(&cache_file, &body) {
// Non-fatal: just warn via stderr-safe approach
let _ = e;
eprintln!("warning: failed to write discovery cache to {}: {}", cache_file.display(), e);
}
if let Err(e) = std::fs::write(&cache_file, &body) {
use std::io::Write;
let _ = writeln!(std::io::stderr(), "warning: failed to write discovery cache to {}: {}", cache_file.display(), e);
}


let doc: RestDescription = serde_json::from_str(&body)?;
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